The use of transparent glazing materials utilizing polycarbonate resin as a structural component for windows, windshields and the like are well known. While these polycarbonate resins are easily fabricated into the desired shape and have excellent physical and chemical properties, such as being less dense than glass and having more breakage resistance than glass, their abrasion, scratch and mar resistance is relatively low and they are adversely affected by prolonged exposure to ultraviolet light.
In order to overcome this relatively low scratch and mar resistance, various coatings have been applied to these polycarbonate resins. U.S. Pat. Nos. 3,451,838, 3,986,997 and 4,027,073 disclose organopolysiloxane coating compositions and techniques for the application of organopolysiloxane coatings onto these surfaces. While these coatings have many desirable properties, e.g., they are hard, mar-resistant, scratch-resistant, and chemical solvent resistant, these organopolysiloxane coatings do not in all instances possess the desired degree of uniform adherence to and durability on the polycarbonate surfaces. In order to improve the adhesion of the organopolysiloxane coatings to the substrate, the prior art, as for example U.S. Pat. No. 3,707,397, has suggested priming the substrates prior to application of the organopolysiloxane coatings thereon.
The difficulty in applying an adhesion promoting primer to the polycarbonate resides in the polycarbonate resins' susceptibility to attack and degradation by some of the more active chemical materials, which materials may be present either in the primer itself or in the delivery system of the primer. Thus, the primer must not only act as an adhesion promoter between the organopolysiloxane and the polycarbonate, but must also be compatible with both the polycarbonate and the organopolysiloxane. Furthermore, not only must the primer itself be compatible with both the polycarbonate and the organopolysiloxane coating, but the delivery system by which the primer is applied onto the polycarbonate must not deleteriously affect the polycarbonate. Since the prior art generally teaches the delivery of the primer as a solution of the primer material dissolved in an organic solvent, and since many of these organic solvents aggressively attack the polycarbonate, such a means of applying a primer to a polycarbonate is not very effective or practical in producing mar-resistant coated polycarbonate articles.
There thus exists a need for polycarbonate articles having uniformly, tenaciously and durably adhered scratch, mar, abrasion, ultraviolet light and chemical solvent resistant coatings thereon and for a method of applying such coatings, and it is a primary object of the present invention to provide such articles and an effective method for producing these articles.